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<head>
    <meta charset="UTF-8">
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    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>
    <!--  手机号 ： 1开头 第二位是3456789 且 11位 -->
    <script>
        
        
        
        
        
        
        // var str = "16618886666";
        // var reg = /^1[3456789]\d{9}/; 
        // console.log(reg.test(str));
       
        
        var str1 = "15814280396";
        var reg = /^1[3456789]\d{9}$/;
        console.log(reg.test(str1));


    </script>
</body>
</html>